fix no reasoning token issue

qwen3_6_scripts/serving_chat.py

@@ -560,9 +560,14 @@ class OpenAIServingChat(OpenAIServing):
                     # if the message delta is None (e.g. because it was a
                     # "control token" for tool calls or the parser otherwise
                     # wasn't ready to send a token, then
-                    #   get the next token without streaming a chunk
+                    #   get the next token without streaming a chunk.
+                    # However, if this is the finish token we must NOT skip —
+                    # the finish block updates reasoning_token_counts, sets
+                    # finish_reason_sent, and flushes the final usage chunk.
                     if delta_message is None:
-                        continue
+                        if output.finish_reason is None:
+                            continue
+                        delta_message = DeltaMessage()
 
                     if output.finish_reason is None:
                         # Send token-by-token response for each request.n